As wireless communications technologies develop, various future evolved wireless communications systems are emerging on the basis of a current wireless communications system. A future evolved wireless communications system may implement communication in a non-standalone working manner by using another existing wireless communications system.
For example, as shown in FIG. 1, a terminal device accesses a base station in a future evolved wireless communications system. The base station is referred to as a “future evolved base station” for short. Then the terminal device accesses a core network in a long term evolution (LTE) system by using an LTE base station connected to the future evolved base station.
Therefore, in a future evolved wireless communications system, after a terminal device initiates an access request (for example, a connection setup request), a network device in an existing wireless communications system needs to be selected for the terminal device, and the terminal device accesses a core network in the existing wireless communications system by using the selected network device. Herein, the selected network device is referred to as an “anchor network device”.
A current cell access procedure is no longer applicable to a wireless communications system having an anchor network device.